uv pip compile --universal outputs requirements with python_version < '0' marker

[notatallshaw-gts]

uv 0.4.28

requirements.in:

apache-airflow[microsoft.azure]==2.3.4
scikit-learn==1.2.2
ipython>=8.4.0
mypy
black

constraints.txt:

apache-airflow-providers-microsoft-azure==4.2.0
attrs==22.1.0
azure-identity==1.10.0
click==8.1.3
colorama==0.4.5
markdown-it-py==2.1.0
msal-extensions==1.0.0
msrestazure==0.6.4
numpy==1.22.4
packaging==21.3
portalocker==2.5.1
typing_extensions==4.3.0

Command:

$ uv pip compile requirements.in -c constraints.txt  --annotation-style line --python 3.10 --universal | grep "'0'"
Resolved 190 packages in 740ms
apache-airflow-providers-ftp==3.11.1 ; python_version < '0'  # via apache-airflow
apache-airflow-providers-http==4.13.1 ; python_version < '0'  # via apache-airflow
apache-airflow-providers-imap==3.7.0 ; python_version < '0'  # via apache-airflow
apache-airflow-providers-sqlite==3.9.0 ; python_version < '0'  # via apache-airflow
azure-core==1.31.0 ; python_version < '0'  # via azure-identity
azure-cosmos==4.7.0 ; python_version < '0'  # via apache-airflow-providers-microsoft-azure
azure-keyvault-secrets==4.9.0 ; python_version < '0'  # via apache-airflow-providers-microsoft-azure
azure-mgmt-resource==23.2.0 ; python_version < '0'  # via apache-airflow-providers-microsoft-azure
azure-servicebus==7.12.3 ; python_version < '0'  # via apache-airflow-providers-microsoft-azure
black==24.10.0 ; python_version < '0'  # via -r requirements.in
cattrs==24.1.2 ; python_version < '0'  # via apache-airflow
connexion==3.1.0 ; python_version < '0'  # via apache-airflow
jsonschema==4.23.0 ; python_version < '0'  # via apache-airflow, flask-appbuilder
mypy==1.13.0 ; python_version < '0'  # via -r requirements.in
rich==13.9.3 ; python_version < '0'  # via apache-airflow
scipy==1.14.1 ; python_version < '0'  # via scikit-learn

[BurntSushi]

I'll take a closer look at this tomorrow. Do you have an expected result? Or just stumbled across the strange output?

[notatallshaw-gts]

This is an MRE derived from a real requirements set. I think the output file still works, for every python_version < '0' marker there is a requirement above it (on a different version) without a marker, e.g.

rich==13.3.1              # via apache-airflow
rich==13.9.3 ; python_version < '0'  # via apache-airflow

I would expect the lines with the python_version < '0' to not be in the output, appears to be some internal resolver state?

[BurntSushi]

@notatallshaw-gts Thanks for the excellent repro! This should be fixed by #8759.